This is soemthing that interests me quite a bit, I don't know about you, but
I find my case too noisy... Monster-Hardware looks
at some CAE Sound Dampening Sheets.
Most every fan I tested measured at least 10 to 12 DB higher than the manufacturer
stated specs. After testing several different fans from various manufacturers,
the only conclusion I can draw from this is that most manufacturers are simply
lying about how many db's their fans produce.